Diederik Hentenaar

60 Chapter 3 corresponding baseline parameters BoP, SoP, Plq, PPD and MBL (i.e., crude analysis). Then, the primary and secondary outcomes were analysed while controlling for the baseline values and confounding effects (i.e., adjusted analysis). The following a priori defined confounders were used in the adjusted mixed model: history of periodontitis (dichotome), smoking, prosthetic design (nominal) and mean periodontal plaque level at T3 (linear). For skewed data (SoP and Plq) a gamma distribution was used. The full mouth periodontal outcomes, VAS scores, midbuccal recession were analysed using an independent sampled t-test. A paired sampled t-test was applied to analyse differences in overall mean full mouth periodontal outcomes before and after therapy. The log- transformed mean peri-implant and periodontal microbiological outcomes were analysed at T3 using a Mann-Whitney U test was used (for between group differences). The data collected at 6, 9 and 12 months (for successfully treated patients at 3 month evaluation) is presented with descriptive statistics. RESULTS The flow of patients throughout the present study is depicted in Figure 1. The overall baseline patient and implant characteristics are shown in Table 1. Baseline characteristics of the successful subjects are described in Table 2. Patients, aged between 25-77 years (mean age 58 years, SD±12.3), were randomly allocated to receive air-polishing ( n = 39) or ultrasonic scaling ( n = 40). Four patients (6 implants) were lost to follow-up between baseline, intervention and 3 month evaluation (see Figure 1), yielding 76 patients with 133 implants, i.e., 38 patients/63 implants in the air-polishing group and 38 patients/70 implants in the ultrasonic group, available for analysis. Patients’ baseline and 3 month follow-up clinical and radiographical outcomes are shown in Table 3a. An overview of the successful patient outcomes (at baseline, T3, T6, T9 and T12) is presented in Table 3b. Mixed model outcomes for the mean difference in BoP, SoP, Plq, PPD and MBL between both groups at T3 are shown in Table 5. The log-transformed mean (SD) of the selected putative periodontal pathogens of the pooled peri-implantitis samples and pooled periodontal samples (in partial edentulous patients) is presented in Table 6. The number of patients with positive samples (%) before and after therapy are presented in Figure 2.